Thermally tunable THz modulator based on a metasurface with VO₂

This study introduces a "C"-shaped terahertz (THz) metasurface modulator that leverages the phase transition properties of vanadium dioxide (VO₂) between its metallic and insulating states. The resonant frequencies of the modulator are tunable by the structural geometric parameters. At low temperatures, the single resonance mode is primarily driven by the longitudinal metal arm, whereas at high temperatures, the single resonance mode is dominated by the transverse arm of VO₂, transitioning to the metallic phase. The modulation achieves a modulation depth exceeding 50% across four filling methods, and reaching a maximum of 97% at 0.405 THz. Additionally, it demonstrates high-temperature sensitivity, achieving a value of 0.046/°C in the range of 50-74°C. These results highlight the excellent modulation performance and temperature-sensing capabilities of the proposed metasurface modulator. With potential applications in smart windows, sensors, and 6G communications, this work offers valuable insights into advancing THz functional devices and improving their performance and practicality.